BDNF and fibromyalgia: In human, increased serum BDNF has been consistently reported in chronic pain conditions such as fibromyalgia (Laske et al., 2007; Zanette et al., 2014), chronic musculoskeletal pain (Caumo et al., 2016), chronic tension-type headache and myofascial pain syndrome (Deitos et al., 2015).